Recording apparatus, recording method, reproducing apparatus, and reproducing method

ABSTRACT

A recording apparatus is disclosed, that comprises a compression process means for compressing an input digital signal corresponding to a predetermined compression process and segmenting the compressed digital signal into blocks, a fixed value generating means for generating a predetermined fixed value, an adding means for adding the fixed value generated by the fixed value generating means at a predetermined timing to the blocks of the digital signal compressed by the compression process means, an encrypting means for encrypting the fixed value and the compressed digital signal added by the adding means, and a recording means for recording the fixed value and the compressed digital signal encrypted by the encrypting means to a record medium.

This is a Continuation of U.S. application Ser. No. 09/674,651, filedNov. 2, 2000, which is incorporated by reference in its entirety herein.

TECHNICAL FIELD

The present invention relates to a recording apparatus, a recordingmethod, a reproducing apparatus, and a reproducing method that permit orprohibit a decompressing process depending on whether or not fixed valuedata that has been placed in each segmented block of a compresseddigital signal and encrypted can be completely decrypted.

RELATED ART

EEPROM (Electrically Erasable Programmable ROM) that is an electricallyrewritable memory requires a large space because each bit is composed oftwo transistors. Thus, the integration of EEPROM is restricted. To solvethis problem, a flash memory that allows one bit to be accomplished withone transistor using all-bit-erase system has been developed. The flashmemory is being expected as a successor of conventional record mediumssuch as magnetic disks and optical discs.

A memory card using a flash memory is also known. The memory card can befreely attached to an apparatus and detached therefrom. A digital audiorecording/reproducing apparatus that uses a memory card instead of aconventional CD (Compact Disc: Trademark) or MD (Mini Disc: Trademark)can be accomplished and a digital audio data that uses the memory cardcan be recorded and reproduced.

A file management system used for a conventional personal computer isnamed FAT (File Allocation Table). In the FAT system, when a particularfile is defined, predetermined parameters are successively set to thefile. Thus, the size of a file becomes variable. One file is composed ofat least one management unit (sector, cluster, or the like). Datacorresponding to the management unit is written to a table referred toas FAT. In the FAT file system, a file structure can be easily formedregardless of the physical characteristics of a record medium. Thus, theFAT file system can be used for a magneto-optical disc as well as afloppy disk and a hard disk. In the above-mentioned memory card, the FATfile system is used.

In recent years, with respect to digital recording of music data, therights of copyright owners should be adequately protected. In otherwords, using technologies of personal computers, digital music data canbe easily copied. To prevent digital music data from being illegallycopied, a next generation audio data that is encrypted has beenproposed.

When audio data is encrypted, it is randomized. Thus, even if thereproduced output data is abnormal due to a particular cause of therecorder, it is difficult to detect the abnormality of the output data.If the abnormality of the reproduced output data cannot be detected,noise such as click sound hurts the ears of the user. Alternatively, thenoise may damage the speakers.

Therefore, an object of the present invention is to provide a recordingapparatus, a recording method, a reproducing apparatus, and reproducingmethod that prevent abnormally reproduced output data from being outputeven in the case that audio data is encrypted.

DISCLOSURE OF THE INVENTION

A first aspect of the present invention is a recording apparatus,comprising a compression process means for compressing an input digitalsignal corresponding to a predetermined compression process andsegmenting the compressed digital signal into blocks, a fixed valuegenerating means for generating a predetermined fixed value an addingmeans for adding the fixed value generated by the fixed value generatingmeans at a predetermined timing to the blocks of the digital signalcompressed by the compression process means, an encrypting means forencrypting the fixed value and the compressed digital signal added bythe adding means, and a recording means for recording the fixed valueand the compressed digital signal encrypted by the encrypting means to arecord medium.

A second aspect of the present invention is a reproducing apparatus forreproducing data of which a digital signal of which a fixed value isadded at a predetermined timing to blocks of main data is compressed andencrypted from a record medium, comprising a decrypting means fordecrypting the compressed and encrypted digital signal, a separatingmeans for separating the fixed value and the compressed data from thedigital signal that are decrypted by the decrypting means, adecompressing means for decompressing the compressed main data separatedby the separating means, a memory means for pre-storing a fixed value, acomparing means for comparing the fixed value separated by theseparating means with the fixed value stored in the memory means, and acontrolling means for permitting and prohibiting the decompressingprocess of the decompressing means for the main data decompressed by thedecompressing means corresponding to the compared result of thecomparing means.

According to the present invention, one block as an erase unit of anattachable/detachable non-volatile memory contains a header and aplurality of sound units SU. The first one byte of the first sound unitSU of the block is read. The high order six bits of the one byte arecompared with a predetermined code (fixed value). When they match, it isdetermined that the reproduced output is not abnormal. On the otherhand, when they do not match, it is determined that the reproducedoutput data is abnormal. When the determined result represents that thereproduced output data is abnormal, the reproduced sound is muted. Onthe other hand, when data is reproduced, an alarm is issued.Alternatively, the system is reset so that the user determines whetheror not the abnormality of the reproduced output data is solved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing the structure of a digital audiorecorder/player using a non-volatile memory card according to thepresent invention;

FIG. 2 is a block diagram showing the internal structure of a DSP 30according to the present invention;

FIG. 3 is a block diagram showing the internal structure of a memorycard 40 according to the present invention;

FIG. 4 is a schematic diagram showing a file management structure of amemory card as a storage medium according to the present invention;

FIG. 5 is a schematic diagram showing the physical structure of data ina flash memory 42 of the memory card 40 according to the presentinvention;

FIG. 6 is a data structure of the memory card 40 according to thepresent invention;

FIG. 7 is a schematic diagram showing the hierarchy of the filestructure in the memory card 40;

FIG. 8 is a schematic diagram showing the data structure of areproduction management file PBLIST.MSF that is a sub directory storedin the memory card 40;

FIG. 9 is a schematic diagram showing the data structure in the casethat one ATRAC3 data file is divided into blocks with a predeterminedunit length and that attribute files are added thereto;

FIG. 10A is a schematic diagram showing the file structure before twofiles are edited with a combining process;

FIG. 10B is a schematic diagram showing the file structure after twofiles are edited with a combining process;

FIG. 10C is a schematic diagram showing the file structure after onefile is edited with a dividing process;

FIG. 11 is a schematic diagram showing the data structure of areproduction management file PBLIST;

FIG. 12A is a schematic diagram showing the data structure of a headerportion of the reproduction management file PBLIST;

FIG. 12B is a schematic diagram showing the data structure of a maindata portion of the reproduction management file PBLIST;

FIG. 12C is a schematic diagram showing the data structure of anadditional information data portion of the reproduction management filePBLIST;

FIG. 13 is a table that correlates types of additional information dataand code values thereof;

FIG. 14 is a table that correlates types of additional information dataand code values thereof;

FIG. 15 is a table that correlates types of additional information dataand code values thereof;

FIG. 16A is a schematic diagram showing the data structure of additionalinformation data;

FIG. 16B is a schematic diagram showing the data structure in the casethat additional information data is an artist name;

FIG. 16C is a schematic diagram showing the data structure in the casethat additional information data is a copyright code;

FIG. 16D is a schematic diagram showing the data structure in the casethat additional information data is date/time information;

FIG. 16E is a schematic diagram showing the data structure in the casethat additional information data is a reproduction log;

FIG. 17 is a schematic diagram showing a detailed data structure of anATRAC3 data file;

FIG. 18 is a schematic diagram showing the data structure of an upperportion of an attribute header that composes an ATRAC3 data file;

FIG. 19 is a schematic diagram showing the data structure of a middleportion of the attribute header that composes an ATRAC3 data file;

FIG. 20 is a table that correlates record modes, record time, and soforth;

FIG. 21 is a table showing copy control states;

FIG. 22 is a schematic diagram showing the data structure of a lowerportion of the attribute header that composes an ATRAC3 data file;

FIG. 23 is a schematic diagram showing the data structure of a header ofa data block of an ATRAC3 data file;

FIGS. 24A to 24C are flow charts showing a recovering method accordingto the present invention in the case that an FTA area was destroyed;

FIG. 25 is a schematic diagram showing the file structure in the memorycard 40 according to a second embodiment of the present invention;

FIG. 26 is a schematic diagram showing the relation between a trackinformation management file TRKLIST.MSF and an ATRAC3 data fileA3Dnnnnn.MSA;

FIG. 27 is a schematic diagram showing the detailed data structure ofthe track information management file TRKLIST.MSF;

FIG. 28 is a schematic diagram showing the detailed data structure ofNAME1 for managing a name;

FIG. 29 is a schematic diagram showing the detailed data structure ofNAME2 for managing a name;

FIG. 30 is a schematic diagram showing the detailed data structure of anATRAC3 data file A3Dnnnnn.MSA;

FIG. 31 is a schematic diagram showing the detailed data structure ofINFLIST.MSF that represents additional information;

FIG. 32 is a schematic diagram showing the detailed data structure ofINFLIST.MSF that represents additional information data;

FIG. 33 is a flow chart showing a recovering method according to thesecond embodiment of the present invention in the case that an FTA areawas destroyed;

FIG. 34 is a block diagram showing the structure of a modulating anddemodulating unit;

FIG. 35 is a schematic diagram showing the data structure of which afixed value is added at intervals of a sound unit SU;

FIG. 36 is a block diagram showing the structure of a decrypting unit;and

FIG. 37 is a block diagram showing the structure of a recording andreproducing apparatus.

BEST MODES FOR CARRYING OUT THE INVENTION

Next, an embodiment of the present invention will be described. FIG. 1is a block diagram showing the structure of a digital audiorecorder/player using a memory card according to an embodiment of thepresent invention. The digital audio recorder/player records andreproduces a digital audio signal using a detachable memory card. Inreality, the recorder/player composes an audio system along with anamplifying unit, a speaker, a CD player, an MD recorder, a tuner, and soforth. However, it should be noted that the present invention can beapplied to other audio recorders. In other words, the present inventioncan be applied to a portable recording/reproducing apparatus. Inaddition the present invention can be applied to a set top box thatrecords a digital audio data that is circulated as a satellite datacommunication, a digital broadcast, or Internet. Moreover, the presentinvention can be applied to a system that records/reproduces movingpicture data and still picture data rather than audio data. The systemaccording to the embodiment of the present invention can record andreproduce additional information such as picture and text other than adigital audio signal.

The recording/reproducing apparatus has an audio encoder/decoder IC 10,a security IC 20, a DSP (Digital Signal Processor) 30. Each of thesedevices is composed of a one-chip IC. The recording/reproducingapparatus has a detachable memory card 40. The one-chip IC of the memorycard 40 has flash memory (nonvolatile memory), a memory control block,and a security block. The security block has a DES (Data EncryptionStandard) encrypting circuit. According to the embodiment, therecording/reproducing apparatus may use a microcomputer instead of theDSP 30.

The audio encoder/decoder IC 10 has an audio interface 11 and anencoder/decoder block 12. The encoder/decoder block 12 encodes a digitalaudio data corresponding to a highly efficient encoding method andwrites the encoded data to the memory card 40. In addition, theencoder/decoder block 12 decodes encoded data that is read from thememory card 40. As the highly efficient encoding method, the ATRAC3format that is a modification of the ATRAC (Adaptive Transform AcousticCoding) format used in Mini-Disc is used.

In the ATRAC3 format, audio data sampled at 44.1 kHz and quantized with16 bits is highly efficiently encoded. In the ATRAC3 format, the minimumdata unit of audio data that is processed is a sound unit (SU). 1 SU isdata of which data of 1024 samples (1024×16 bits×2 channels) iscompressed to data of several hundred bytes. The duration of 1 SU isaround 23 msec. In the highly efficient encoding method, the data amountof audio data is compressed to data that is around 10 times smaller thanthat of original data. As with the ATRAC1 format used in Mini-Disc, theaudio signal compressed and decompressed corresponding to the ATRAC3format less deteriorates in the audio quality.

A line input selector 13 selectively supplies the reproduction outputsignal of an MD, the output signal of a tuner, or a reproduction outputsignal of a tape to an A/D converter 14. The A/D converter 14 convertsthe input line signal to a digital audio signal (sampling frequency=44.1kHz; the number of quantizing bits=16). A digital input selector 16selectively supplies a digital output signal of an MD, a CD, or a CS(Satellite Digital Broadcast) to a digital input receiver 17. Thedigital input signal is transmitted through for example an opticalcable. An output signal of the digital input receiver 17 is supplied toa sampling rate converter 15. The sampling rate converter 15 convertsthe digital input signal into a digital audio signal (samplingfrequency=44.1 kHz; the number of quantizing bits=16).

The encoder/decoder block 12 of the audio encoder/decoder IC 10 suppliesencoded data to a DES encrypting circuit 22 through an interface 21 ofthe security IC 20. The DES encrypting circuit 22 has a FIFO 23. The DESencrypting circuit 22 is disposed so as to protect the copyright ofcontents. The memory card 40 also has a DES encrypting circuit. The DESencrypting circuit 22 of the recording/reproducing apparatus has aplurality of master keys and an apparatus unique storage key. The DESencrypting circuit 22 also has a random number generating circuit. TheDES encrypting circuit 22 can share an authenticating process and asession key with the memory card 40 that has the DES encrypting circuit.In addition, the DES encrypting circuit 22 can re-encrypt data with thestorage key of the DES encrypting circuit.

The encrypted audio data that output from the DES encrypting circuit 22is supplied to a DSP (Digital Signal Processor) 30. The DSP 30communicates with the memory card 40 through an interface. In thisexample, the memory card 40 is attached to an attaching/detachingmechanism (not shown) of the recording/reproducing apparatus. The DSP 30writes the encrypted data to the flash memory of the memory card 40. Theencrypted data is serially transmitted between the DSP 30 and the memorycard 40. In addition, an external SRAM (Static Random Access Memory), 31is connected to the DSP 30. The SRAM 31 provides therecording/reproducing apparatus with a sufficient storage capacity so asto control the memory card 40.

A bus interface 32 is connected to the DSP 30. Data is supplied from anexternal controller (not shown) to the DSP 30 through a bus 33. Theexternal controller controls all operations of the audio system. Theexternal controller supplies data such as a record command or areproduction command that is generated corresponding to a user'soperation through an operation portion to the DSP 30 through the businterface 32. In addition, the external controller supplies additionalinformation such as image information and character information to theDSP 30 through the bus interface 32. The bus 33 is a bidirectionalcommunication path. Additional information that is read from the memorycard 40 is supplied to the external controller through the DSP 30, thebus interface 32, and the bus 33. In reality, the external controller isdisposed in for example an amplifying unit of the audio system. Inaddition, the external controller causes a display portion to displayadditional information, the operation state of the recorder, and soforth. The display portion is shared by the audio system. Since datathat is exchanged through the bus 33 is not copyright protected data, itis not encrypted.

The encrypted audio data that is read from the memory card 40 by the DSP30 is decrypted by the security IC 20. The audio encoder/decoder IC 10decodes the encoded data corresponding to the ATRAC3 format. Output dataof the audio encoder/decoder 10 is supplied to a D/A converter 18. TheD/A converter 18 converts the output data of the audio encoder/decoderinto an analog signal. The analog audio signal is supplied to a lineoutput terminal 19.

The analog audio signal is supplied to an amplifying unit (not shown)through the line output terminal 19. The analog audio signal isreproduced from a speaker or a head set. The external controllersupplies a muting signal to the D/A converter 18. When the muting signalrepresents a mute-on state, the external controller prohibits the audiosignal from being output from the line output terminal 19.

FIG. 2 is a block diagram showing the internal structure of the DSP 30.Referring to FIG. 2, the DSP 30 comprises a core 34, a flash memory 35,an SRAM 36, a bus interface 37, a memory card interface 38, andinter-bus bridges. The DSP 30 has the same function as a microcomputer.The core 34 is equivalent to a CPU. The flash memory 35 stores a programthat causes the DSP 30 to perform predetermined processes. The SRAM 36and the external SRAM 31 are used as a RAM of the recording/reproducingapparatus.

The DSP 30 controls a writing process for writing encrypted audio dataand additional information to the memory card 40 corresponding to anoperation signal such as a record command received through the businterfaces 32 and 37 and a reading process for reading them therefrom.In other words, the DSP 30 is disposed between the application softwareside of the audio system that records/reproduces audio data andadditional information and the memory card 40. The DSP 30 is operatedwhen the memory card 40 is accessed. In addition, the DSP 30 is operatedcorresponding to software such as a file system.

The DSP 30 manages files stored in the memory card 40 with the FATsystem used in conventional personal computers. In addition to the filesystem, according to the embodiment of the present invention, amanagement file is used. The management file will be descried later. Themanagement file is used to manage data files stored in the memory card40. The management file as the first file management information is usedto manage audio data files. On the other hand, the FAT as the secondfile management information is used to mange all files including audiodata files and management files stored in the flash memory of the memorycard 40. The management file is stored in the memory card 40. The FAT iswritten to the flash memory along with the route directory and so forthbefore the memory card 40 is shipped. The details of the FAT will bedescribed later.

According to the embodiment of the present invention, to protect thecopyright of data, audio data that has been compressed corresponding tothe ATRAC3 format is encrypted. On the other hand, since it is notnecessary to protect the copyright of the management file, it is notencrypted. There are two types of memory cards that are an encryptiontype and a non-encryption type. However, a memory card for use with therecorder/player that records copyright protected data is limited to theencryption type.

Voice data and image data that are recorded by users are recorded onnon-encryption type memory cards.

FIG. 3 is a block diagram showing the internal structure of the memorycard 40. The memory card 40 comprises a control block 41 and a flashmemory 42 that are structured as a one-chip IC. A bidirectional serialinterface is disposed between the DSP 30 of the recorder/player and thememory card 40. The bidirectional serial interface is composed of tenlines that are a clock line SCK for transmitting a clock signal that istransmitted along with data, a status line SBS for transmitting a signalthat represents a status, a data line DIO for transmitting data, aninterrupt line INT, two GND lines, two INT lines, and two reservedlines.

The clock line SCK is used for transmitting a clock signal insynchronization with data. The status line SBS is used for transmittinga signal that represents the status of the memory card 40. The data lineDIO is used for inputting and outputting a command and encrypted audiodata. The interrupt line INT is used for transmitting an interruptsignal that causes the memory card 40 to interrupt the DSP 30 of therecorder/player. When the memory card 40 is attached to therecorder/player, the memory card 40 generates the interrupt signal.However, according to the embodiment of the present invention, since theinterrupt signal is transmitted through the data line DIO, the interruptline INT is grounded.

A serial/parallel converting, parallel/serial converting, and interfaceblock (S/P, P/S, I/F block) 43 is an interface disposed between the DSP30 of the recorder/player and the control block 41 of the memory card40. The S/P, P/S, and IF block 43 converts serial data received from theDSP 30 of the recorder/player into parallel data and supplies theparallel data to the control block 41. In addition, the S/P, P/S, and IFblock 43 converts parallel data received from the control block 41 intoserial data and supplies the serial data to the DSP 30. When the S/P,P/S, and IF block 43 receives a command and data through the data lineDIO, the S/P, P/S, and IF block 43 separates them into these that arenormally accessed to the flash memory 42 and those that are encrypted.

In the format of which data is transmitted through the data line DIO,after a command is transmitted, data is transmitted. The S/P, P/S, andIF block 43 detects the code of a command and determines whether thecommand and data are those that are normally accessed or those that areencoded. Corresponding to the determined result, the S/P, P/S, and IFblock 43 stores a command that is normally accessed to a commandregister 44 and stores data that is normally accessed to a page buffer45 and a write register 46. In association with the write register 46,the memory card 40 has an error correction code encoding circuit 47. Theerror correction code encoding circuit 47 generates a redundant codethat is an error correction code for data temporarily stored in the pagebuffer 45.

Output data of the command register 44, the page buffer 45, the writeregister 46, and the error correction code encoding circuit 47 issupplied to a flash memory interface and sequencer (hereinafter,referred to as memory I/F and sequencer) 51. The memory IF and sequencer51 is an interface disposed between the control block 41 and the flashmemory 42 and controls data exchanged therebetween. Data is written tothe flash memory through the memory IF and sequencer 51.

Audio data that has been compressed corresponding to the ATRAC3 formatand written to the flash memory (hereinafter, this audio data isreferred to as ATRAC3 data) is encrypted by the security IC 20 of therecorder/player and the security block 52 of the memory card 40 so as toprotect the copyright of the ATRAC3 data. The security block 52comprises a buffer memory 53, a DES encrypting circuit 54, and anonvolatile memory 55.

The security block 52 of the memory card 40 has a plurality ofauthentication keys and a unique storage key for each memory card. Thenonvolatile memory 55 stores a key necessary for encrypting data. Thekey stored in the nonvolatile memory 55 cannot be analyzed. According tothe embodiment, for example, a storage key is stored in the nonvolatilememory 55. The security block 52 also has a random number generatingcircuit. The security block 52 authenticates an applicablerecorder/player and shares a session key therewith. In addition, thesecurity block 52 re-encrypts contents with the storage key through theDSE-encrypting circuit 54.

For example, when the memory card 40 is attached to the recorder/player,they are mutually authenticated. The security IC 20 of therecorder/player and the security block 52 of the memory card 40 mutuallyauthenticate. When the recorder/player has authenticated the attachedmemory card 40 as an applicable memory card and the memory card 40 hasauthenticated the recorder/player as an applicable recorder/player, theyare mutually authenticated. After the mutual authenticating process hasbeen successfully performed, the recorder/player and the memory card 40generate respective session keys and share them with each other.Whenever the recorder/player and the memory card 40 authenticate eachother, they generate respective session keys.

When contents are written to the memory card 40, the recorder/playerencrypts a contents key with a session key and supplies the encrypteddata to the memory card 40. The memory card 40 decrypts the contents keywith the session key, re-encrypts the contents key with a storage key,and supplies the contents key to the recorder/player. The storage key isa unique key for each memory card 40. When the recorder/player receivesthe encrypted contents key, the recorder/player performs a formattingprocess for the encrypted contents key, and writes the encryptedcontents key and the encrypted contents to the memory card 40.

In the above section, the writing process for the memory card 40 wasdescribed. In the following, the reading process for the memory card 40will be described. Data that is read from the flash memory 42 issupplied to the page buffer 45, the read register 48, and the errorcorrection circuit 49 through the memory IF and the sequencer 51. Theerror correcting circuit 49 corrects an error of the data stored in thepage buffer 45. Output data of the page buffer 45 that has beenerror-corrected and the output data of the read register 48 are suppliedto the S/P, P/S, and IF block 43. The output data of the S/P, P/S, andIF block 43 is supplied to the DSP 30 of the recorder/player through theabove-described serial interface.

When data is read from the memory card 40, the contents key encryptedwith the storage key and the contents encrypted with the block key areread from the flash memory 42. The security block 52 decrypts thecontents key with the storage key. The security block 52 re-encrypts thedecrypted content key with the session key and transmits there-encrypted contents key to the recorder/player. The recorder/playerdecrypts the contents key with the received session key and generates ablock key with the decrypted contents key. The recorder/playersuccessively decrypts the encrypted ATRAC3 data.

A config. ROM 50 is a memory that stores partition information, varioustypes of attribute information, and so forth of, the memory card 40. Thememory card 40 also has an erase protection switch 60. When the switch60 is in the erase protection position, even if a command that causesthe memory card 40 to erase data stored in the flash memory 42 issupplied from the recorder/player side to the memory card 40, the memorycard 40 is prohibited from erasing the data stored in the flash memory42. An OSC cont. 61 is an oscillator that generates a clock signal thatis the reference of the timing of the process of the memory card 40.

FIG. 4 is a schematic diagram showing the hierarchy of the processes ofthe file system of the computer system that uses a memory card as astorage medium. On the hierarchy, the top hierarchical level is anapplication process layer. The application process layer is followed bya file management process layer, a logical address management layer, aphysical address management layer, and a flash memory access layer. Inthe above-mentioned hierarchical structure, the file management processlayer is the FAT file system. Physical addresses are assigned toindividual blocks of the flash memory. The relation between the blocksof the flash memory and the physical addresses thereof does not vary.Logical addresses are addresses that are logically handled on the filemanagement process layer.

FIG. 5 is a schematic diagram showing the physical structure of datahandled in the flash memory 42 of the memory card 40. In the memory 42,a data unit (referred to as segment) is divided into a predeterminednumber of blocks (fixed length). One block is divided into apredetermined number of pages (fixed length). In the flash memory, datais erased as each block at a time. Data is written to the flash memory42 or read therefrom as a page at a time. The size of each block is thesame. Likewise, the size of each page is the same. One block is composedof page 0 to page m. For example, one block has a storage capacity offor example 8 KB (kilobytes) or 16 KB. One page has a storage capacityof 512 B (bytes). When one block has a storage capacity of 8 KB, thetotal storage capacity of the flash memory 42 is 4 MB (512 blocks) or 8MB (1024 blocks). When one block has a storage capacity of 16 KB, thetotal storage capacity of the flash memory 42 is 16 MB (1024 blocks), 32MB (2048 blocks), or 64 MB (4096 blocks).

One page is composed of a data portion of 512 bytes and a redundantportion of 16 bytes. The first three bytes of the redundant portion isan overwrite portion that is rewritten whenever data is updated. Thefirst three bytes successively contain a block status area, a pagestatus area, and an update status area. The remaining 13 bytes of theredundant portion are fixed data that depends on the contents of thedata portion. The 13 bytes contain a management flag area (1 byte), alogical address area (2 bytes), a format reserve area (5 bytes), adispersion information ECC area (2 bytes), and a data ECC area (3bytes). The dispersion information ECC area contains redundant data foran error correction process against the management flag area, thelogical address area, and the format reserve area. The data ECC areacontains redundant data for an error correction process against 512-bytedata.

The management flag area contains a system flag (1: user block, 0: bootblock), a conversion table flag (1: invalid, 0: table block), a copyprohibition flag (1: OK, 0: NG), and an access permission flag (1: free,0: read protect).

The first two blocks—blocks 0 and 1 are boot blocks. The block 1 is abackup of the block 0. The boot blocks are top blocks that are valid inthe memory card. When the memory card is attached to therecorder/player, the boot blocks are accessed at first. The remainingblocks are user blocks. Page 0 of the boot block contains a header area,a system entry area, and a boot and attribute information area. Page 1of the boot block contains a prohibited block data area. Page 2 of theboot block contains a CIS (Card Information Structure)/IDI (identifyDrive Information) area.

The header area of the boot block contains a boot block ID and thenumber of effective entries. The system entries are the start positionof prohibited block data, the data size thereof, the data type thereof,the data start position of the CIS/IDI area, the data size thereof, andthe data type thereof. The boot and attribute information contains thememory card type (read only type, rewritable type, or hybrid type), theblock size, the number of blocks, the number of total blocks, thesecurity/non-security type, the card fabrication data (date offabrication), and so forth.

Since the flash memory has a restriction for the number of rewrite timesdue to the deterioration of the insulation film, it is necessary toprevent the same storage area (block) from being concentratedlyaccessed. Thus, when data at a particular logical address stored at aparticular physical address is rewritten, updated data of a particularblock is written to a non-used block rather than the original block.Thus, after data is updated, the relation between the logical addressand the physical address changes. This process is referred to as swapprocess. Consequently, the same block is prevented from beingconcentratedly accessed. Thus, the service life of the flash memory canbe prolonged.

The logical address associates with data written to the block. Even ifthe block of the original data is different from the block of updateddata, the address on the FAT does not change. Thus, the same data can beproperly accessed. However, since the swap process is performed, aconversion table that correlates logical addresses and physicaladdresses is required (this table is referred to as logical-physicaladdress conversion table). With reference to the logical-physicaladdress conversion table, a physical address corresponding to a logicaladdress designated on the FAT is obtained. Thus, a block designated witha physical address can be accessed.

The DSP 30 stores the logical-physical address conversion table in theSRAM. When the storage capacity of the RAM is small, thelogical-physical address conversion table can be stored to the flashmemory. The logical physical address conversion table correlates logicaladdresses (2 bytes) sorted in the ascending order with physicaladdresses (2 bytes). Since the maximum storage capacity of the flashmemory is 128 MB (8192 blocks), 8192 addresses can be assigned with twobytes. The logical-physical address conversion table is managed for eachsegment. Thus, the size of the logical-physical address conversion tableis proportional to the storage capacity of the flash memory. When thestorage capacity of the flash memory is 8 MB (two segments), two pagesare used as the logical-physical address conversion table for each ofthe segments. When the conversion table is stored in the flash memory, apredetermined one bit of the management flag area in the redundantportion in each page represents whether or not the current block is ablock containing the logical-physical address conversion table.

The above-described memory card can be used with the FAT file system ofa personal computer system as with the disc shaped record medium. Theflash memory has an IPL area, a FAT area, and a route directory area(not shown in FIG. 5). The IPL area contains the address of a program tobe initially loaded to the memory of the recorder/player. In addition,the IPL area contains various types of memory information. The FAT areacontains information with respect to blocks (clusters). The FAT hasdefined unused blocks, next block number, defective blocks, and lastblock number. The route directory area contains directory entries thatare a file attribute, an update date [day, month, year], file size, andso forth.

Next, with reference to FIG. 6, a managing method using the FAT tablewill be described.

FIG. 6 is a schematic diagram showing a memory map. The top area of thememory map is a partition table portion. The partition table portion isfollowed by a block area, a boot sector, a FAT area, a FAT backup area,a root directory area, a sub directory area, and a data area. On thememory map, logical addresses have been converted into physicaladdresses corresponding to the logical-physical address conversiontable.

The boot sector, the FAT area, the FAT backup area, the root directoryarea, the sub-directory area, and the data area are referred to as FATpartition area.

The partition table portion contains the start address and the endaddress of the FAT partition area.

The FAT used for a conventional floppy disk does not have such apartition table. Since the first track has only a partition table, thereis a blank area. The boot sector contains the size of the FAT structure(12 bit FAT or 16 bit FAT), the cluster size, and the size of each area.The FAT is used to manage the position of a file recorded in the dataarea. The FAT copy area is a FAT backup area. The route directory areacontains file names, start cluster addresses thereof, and variousattributes thereof. The route directory area uses 32 bytes per file.

The sub directory area is achieved by a directory attribute file as adirectory. In the embodiment shown in FIG. 6, the sub directory area hasfour files named PBLIST.MSF, CAT.MSF, DOG.MSF, and MAN.MFA. The subdirectory area is used to manage file names and record positions on theFAT. In other words, the slot of the file name CAT.MSF is assignedaddress “10” on the FAT. The slot of the file name DOG.MSF is assignedaddress “10” on the FAT. An area after cluster 2 is used as a data area.In this embodiment, audio data that has been compressed corresponding tothe ATRAC3 format is recorded. The top slot of the file name MAN.MSA isassigned address “110” on the FAT. According to the embodiment of thepresent invention, audio data with the file name CAT.MSF is recorded tocluster 5 to 8. Audio data of DOG-1 as the first half of the file withthe file name DOG.MSF is recorded to clusters 10 to 12. Audio data DOG-2as the second half of the file with the file name DOG.MSF is recorded inclusters 100 and 101. Audio data with the file name MAN.MSF is recordedin clusters 110 and 111.

In the embodiment of the present invention, an example of which a singlefile is divided into two portions and dispersedly recorded is described.In the embodiment, an area “Empty” in the data area is a recordablearea. An area after cluster 200 is used for managing file names. Thefile CAT.MSF is recorded to cluster 200. The file DOG.MSF is recorded tocluster 201. The file MAN.MSF is recorded to cluster 202. When thepositions of the files are changed, the area after cluster 200 isre-arranged. When the memory card is attached, the beginning and the endof the FAT partition area are recorded with reference to the toppartition table portion. After the boot sector portion is reproduced,the root directory area and the sub directory area are reproduced. Theslot of the reproduction management information PBLIST.MSF in the subdirectory area is detected. Thus, the address of the end portion of theslot of the file PBLIST.MSF is obtained. In the embodiment, sinceaddress “200” is recorded at the end of the file PBLIST.MSF, cluster 200is referenced.

The area after cluster 200 is used for managing the reproduction orderof files. In the embodiment, the file CAT.MSA is the first program. Thefile DOG.MSA is the second program. The file MAN.MSA is the thirdprogram. After the area after cluster 200 is referenced, slots of thefiles CAT.MSA, DOG.MSA, and MAN.MSA are referenced. In FIG. 6, the endof the slot of the file CAT.MSA is assigned address “5”. The end of theslot of the file DOG.MSA is assigned address “10”. The end of the slotof the file MAN.MSA is assigned address “110”. When an entry address issearched on the FAT with address “5”, cluster address “6” is obtained.When an entry address is searched on the FAT with address “6”, clusteraddress “7” is obtained. When an entry address is searched on the FATwith address “8”, code “FFF” that represents the end is obtained. Thus,the file CAT.MSA uses clusters 5, 6, 7, and 8. With reference toclusters 5, 6, 7, and 8 in the data area, an area of ATRAC3 data withthe file name CAT.MSA can be accessed.

Next, a method for searching the file DOG.MSF that has been dispersedlyrecorded will be described. The end of the slot of the file DOG.MSA isassigned address “10”. When an entry address on the FAT is searched withaddress “10”, cluster address “11” is obtained. When an entry address onthe FAT is searched with address “11” is referenced, cluster address“12” is obtained. When an entry address on the FAT is searched withaddress “12” is referenced, cluster address “101” is obtained. Whenentry address “101” is referenced, code “FFF” that represents the end isobtained. Thus, the file DOG.MSF uses clusters 10, 11, 12, 100, and 101.When clusters 10, 11, and 12 are referenced, the first part of ATRAC3data of the file DOG.MSF can be accessed. When the clusters 100 and 101are referenced, the second part of ATRAC3 data of the file DOG.MSF canbe accessed. In addition, when an entry address is searched on the FATwith address “110”, cluster address “101” is obtained. When an entryaddress “111” is searched on the FAT with address “101”, code “FFF” thatrepresents the end is obtained. Thus, it is clear that the file MAN.MSAuses clusters 110 and 111. As described above, data files dispersed inthe flash memory can be linked and sequentially reproduced.

According to the embodiment of the present invention, in addition to thefile management system defined in the format of the memory card 40, themanagement file is used for managing tracks and parts of music files.The management file is recorded to a user block of the flash memory 42of the memory card 40. Thus, as will be described later, even if the FATof the memory card 40 is destroyed, a file can be recovered.

The management file is generated by the DSP 30. When the power of therecorder/player is turned on, the DSP 30 determines whether or not thememory card 40 has been attached to the recorder/player. When the memorycard has been attached, the DSP 30 authenticates the memory card 40.When the DSP 30 has successfully authenticated the memory card 40, theDSP 30 reads the boot block of the flash memory 42. Thus, the DSP 30reads the physical-logical address conversion table and stores the readdata to the SRAM. The FAT and the route directory have been written tothe flash memory of the memory card 40 before the memory card 40 isshipped. When data is recorded to the memory card 40, the managementfile is generated.

In other words, a record command issued by the remote controller of theuser or the like is supplied to the DSP 30 from the external controllerthrough the bus and the bus interface 32. The encoder/decoder IC 10compresses the received audio data and supplies the resultant ATRAC3data to the security IC 20. The security IC 20 encrypts the ATRAC3 data.The encrypted ATRAC3 data is recorded to the flash memory 42 of thememory card 40. Thereafter, the FAT and the management file are updated.Whenever a file is updated (in reality, whenever the recording processof audio data is completed), the FAT and the management file stored inthe SRAMs 31 and 36 are rewritten. When the memory card 40 is detachedor the power of the recorder/player is turned off, the FAT and themanagement file that are finally supplied from the SRAMs 31 and 36 arerecorded to the flash memory 42. Alternatively, whenever the recordingprocess of audio data is completed, the FAT and the management filewritten in the flash memory 42 may be rewritten. When audio data isedited, the contents of the management file are up dated.

In the data structure according to the embodiment, additionalinformation is contained in the management file. The additionalinformation is updated and recorded to the flash memory 42. In anotherdata structure of the management file, an additional informationmanagement file is generated besides the track management file. Theadditional information is supplied from the external controller to theDSP 30 through the bus and the bus interface 32. The additionalinformation is recorded to the flash memory 42 of the memory card 40.Since the additional information is not supplied to the security IC 20,it is not encrypted. When the memory card 40 is detached from therecorder/player or the power thereof is turned off, the additionalinformation is written from the SRAM of the DSP 30 to the flash memory42.

FIG. 7 is a schematic diagram showing the file structure of the memorycard 40. As the file structure, there are a still picture directory, amoving picture directory, a voice directory, a control directory, and amusic (HIFI) directory. According to the embodiment, music programs arerecorded and reproduced. Next, the music directory will be described.The music directory has two types of files. The first type is areproduction management file BLIST.MSF (hereinafter, referred to asPBLIST). The other type is an ATRAC3 data file A3Dnnnn.MSA that storesencrypted music data. The music directory can stores up to 400 ATRAC3data files (namely, 400 music programs). ATRAC3 data files areregistered to the reproduction management file and generated by therecorder/player.

FIG. 8 is a schematic diagram showing the structure of the reproductionmanagement file. FIG. 9 is a schematic diagram showing the filestructure of one ATRAC3 data file. The reproduction management file is afixed length file of 16 KB. An ATRAC3 data file is composed of anattribute header and an encrypted music data area for each musicprogram. The attribute data has a fixed length of 16 KB. The structureof the attribute header is similar to that of the reproductionmanagement file.

The reproduction management file shown in FIG. 8 is composed of aheader, a memory card name NM-1S (for one byte code), a memory card nameNM2-S (for two byte code), a program reproduction sequence table TRKTBL,and memory card additional information INF-S. The attribute header(shown in FIG. 9) at the beginning of the data file is composed of aheader, a program name NM1 (for one byte code), a program name NM2 (fortwo byte code), track information TRKINF (such as track keyinformation), part information PRTINF, and track additional informationINF. The header contains information of the number of total parts, theattribute of the name, the size of the additional information, and soforth.

The attribute data is followed by ATRAC3 music data. The music data isblock-segmented every 16 KB. Each block starts with a header. The headercontains an initial value for decrypting encrypted data. Only music dataof an ATRAC3 data file is encrypted. Thus, other data such as thereproduction management file, the header, and so forth are notencrypted.

Next, with reference to FIGS. 10A to 10C, the relation between musicprograms and ATRAC3 data files will be described. One track isequivalent to one music program. In addition, one music program iscomposed of one ATRAC3 data (see FIG. 9). The ATRAC3 data file is audiodata that has been compressed corresponding to the ATRAC3 format. TheATRAC3 data file is recorded as a cluster at a time to the memory card40. One cluster has a capacity of 16 KB. A plurality of files are notcontained in one cluster. The minimum data erase unit of the flashmemory 42 is one block. In the case of the memory card 40 for musicdata, a block is a synonym of a cluster. In addition, one cluster isequivalent to one sector.

One music program is basically composed of one part. However, when amusic program is edited, one music program may be composed of aplurality of parts. A part is a unit of data that is successivelyrecorded. Normally, one track is composed of one part. The connection ofparts of a music program is managed with part information PRTINF in theattribute header of each music program. In other words, the part size isrepresented with part size PRTSIZE (4 bytes) of the part informationPRTINF. The first two bytes of the part size PRTSIZE represents thenumber of total clusters of the current part. The next two bytesrepresent the positions of the start sound unit (SU) and the end soundunit (SU) of the beginning and last clusters, respectively. Hereinafter,a sound unit is abbreviated as SU. With such a part notation, when musicdata is edited, the movement of the music data can be suppressed. Whenmusic data is edited for each block, although the movement thereof canbe suppressed, the edit unit of a block is much larger than the editunit of a SU.

SU is the minimum unit of a part. In addition, SU is the minimum dataunit in the case that audio data is compressed corresponding to theATRAC3 format. 1 SU is audio data of which data of 1024 samples at 44.1kHz (1024×16 bits×2 channels) is compressed to data that is around 10times smaller than that of original data. The duration of 1 SU is around23 msec. Normally, one part is composed of several thousand SU. When onecluster is composed of 42 SU, one cluster allows a sound of one secondto be generated. The number of parts composing one track depends on thesize of the additional information. Since the number of parts isobtained by subtracting the header, the program name, the additionaldata, and so forth from one block, when there is no additionalinformation, the maximum number of parts (645 parts) can be used.

FIG. 10A is a schematic diagram showing the file structure in the casethat two music programs of a CD or the like are successively recorded.The first program (file 1) is composed of for example five clusters.Since one cluster cannot contain two files of the first program and thesecond program, the file 2 starts from the beginning of the nextcluster. Thus, the end of the part 1 corresponding to the file 1 is inthe middle of one cluster and the remaining area of the cluster containsno data. Likewise, the second music program (file 2) is composed of onepart. In the case of the file 1, the part size is 5. The first clusterstarts at 0-th SU. The last cluster ends at 4-th SU.

There are four types of edit processes that are a divide process, acombine process, an erase process, and a move process. The divideprocess is performed to divide one track into two portions. When thedivide process is performed, the number of total tracks increases byone. In the divide process, one file is divided into two files on thefile system. Thus, in this case, the reproduction management file andthe FAT are updated. The combine process is performed to combine twotracks into one track. When the combine process is performed, the numberof total tracks decreases by one. In the combine process, two files arecombined into one file on the file system. Thus, when the combineprocess is performed, the reproduction management file and the FAT areupdated. The erase process is performed to erase a track. The tracknumbers after the track that has been erased decrease one by one. Themove process is performed to change the track sequence. Thus, when theerase process or the move process is performed, the reproductionmanagement file and the FAT are updated.

FIG. 10B is a schematic diagram showing the combined result of twoprograms (file 1 and file 2) shown in FIG. 10A. As a result of thecombine process, the combined file is composed of two parts. FIG. 10C isa schematic diagram showing the divided result of which one program(file 1) is divided in the middle of the cluster 2. By the divideprocess, the file 1 is composed of clusters 0, 1, and the beginningportion of cluster 2. The file 2 is composed of the end portion ofcluster 2 and clusters 3 and 4.

As described above, according to the embodiment of the presentinvention, since the part notation is defined, as the combined result(see FIG. 10B), the start position of the part 1, the end position ofthe part 1, and the end portion of the part 2 can be defined with SU.Thus, to pack the space due to the combined result, it is not necessaryto move the music data of the part 2. In addition, as the divided result(see FIG. 10C), it is not necessary to move data and pack the space atthe beginning of the file 2.

FIG. 11 is a schematic diagram showing the detailed data structure ofthe reproduction management file PBLIST. FIGS. 12A and 12B show a headerportion and the remaining portion off the reproduction management filePBLIST. The size of the reproduction management file is one cluster (oneblock=16 KB). The size of the header shown in FIG. 12A is 32 bytes. Therest of the reproduction management file PBLIST shown in FIG. 12Bcontains a name NM1-S area (256 bytes) (for the memory card), a nameNM2-S area (512 bytes), a contents key area, a MAC area, an S-YMDhmsarea, a reproduction sequence management table TRKTBL area (800 bytes),a memory card additional information INF-S area (14720 bytes), and aheader information redundant area. The start positions of these areasare defined in the reproduction management file.

The first 32 bytes of (0x0000) to (0x0010) shown in FIG. 12A are usedfor the header. In the file, 16-byte areas are referred to as slots.Referring to FIG. 12A, the header are placed in the first and secondslots. The header contains the following areas. An area denoted by“Reserved” is an undefined area. Normally, in a reserved area, a null(0x00) is written. However, even if any data is written to a reservedarea, the data written in the reserved is ignored. In a future version,some, reserved areas may be used. In addition, data is prohibited frombeing written to a reserved area. When an option area is not used, it istreated as a reserved area.

=BLKID-TL0 (4 bytes)

Meaning: BLOCKID FILE ID

Function: Identifies the top of the reproduction management file.

Value: Fixed value=“TL=0” (for example, 0x544C2D30)

=MCode (2 bytes)

Meaning: MAKER CODE

Function: Identifies the maker and model of the recorder/player

Value: High-order 10 bits (Maker code); low-order 6 bits (model code).

=REVISION (4 bytes)

Meaning: Number of rewrite times of PBLIST

Function: Increments whenever the reproduction management file isrewritten.

Value: Starts at 0 and increments by 1.

=S-YMDhms (4 bytes) (Option)

Meaning: Year, month, day, hour, minute, and second recorded by therecorder/player with a reliable clock.

Function: Identifies the last recorded date and time.

Value: bits 25 to 31: Year 0 to 99 (1980 to 2079)

-   -   bits 21 to 24: Month 0 to 12    -   bits 16 to 20: Day 0 to 31    -   bits 11 to 15: Hour 0 to 23    -   bits 05 to 10: Minute 0 to 59    -   bits 00 to 04: Second 0 to 29 (two bit interval)

=SY1C+L (2 bytes)

Meaning: Attribute of name (one byte code) of memory card written inNM1-S area.

Function: Represents the character code and the language code as onebyte code.

Value: Character code (C): High-order one byte

-   -   00: Non-character code, binary number    -   01: ASCII (American Standard Code for Information Interchange)    -   02: ASCII+KANA    -   03: Modified 8859-1    -   81: MS-JIS    -   82: KS C 5601-1989    -   83: GB (Great Britain) 2312-80    -   90: S-JIS (Japanese Industrial Standards) (for Voice)        -   Language code (L): Low-order one byte    -   Identifies the language based on EBU Tech 3258    -   standard.    -   00: Not set    -   08: German    -   09: English    -   0A: Spanish    -   0F: French    -   15: Italian    -   1D: Dutch    -   65: Korean    -   69: Japanese    -   75: Chinese    -   When data is not recorded, this area is all 0.

=SN2C+L (2 bytes)

Meaning: Attribute of name of memory card in NM2-S area.

Function: Represents the character code and the language coded as onebyte code.

Value: Same as SN1C+L.

=SINFSIZE (2 bytes)

Meaning: Total size of additional information of memory card in INF-Sarea.

Function: Represents the data size as an increment of 16 bytes. Whendata is not recorded, this area is all 0.

Value: Size: 0x0001 to 0x39C (924)

=T-TRK (2 bytes)

Meaning: TOTAL TRACK NUMBER

Function: Represents the number of total tracks.

Value: 1 to 0x0190 (Max. 400 tracks)

-   -   When data is recorded, this area is all 0.

=VerNo (2 bytes)

Meaning: Format version number

Function: Represents the major version number (high order one byte) andthe minor version number (low order one byte).

Value: 0x0100 (Ver 1.0)

-   -   0x0203 (Ver 2.3)

Next, areas (see FIG. 13B) that preceded by the header will bedescribed.

=NM1-S

Meaning: Name of memory card (as one byte code)

Function: Represents the name of the memory card as one byte code (max.256). At the end of this area, an end code (0x00) is written. The sizeis calculated from the end code. When data is not recorded, null (0x00)is recorded from the beginning (0x0020) of this area for at least onebyte.

Value: Various character code

=NM2-S

Meaning: Name of memory card (as two byte code)

Function: Represents the name of the memory card as two byte code (max.512). At the end of this area, an end code (0x00) is written. The sizeis calculated from the end code. When data is not recorded, null (0x00)is recorded from the beginning (0x0120) of this area for at least twobytes.

Value: Various character code

=CONTENTS KEY

Meaning: Value for music program. Protected with MG(M) and stored. Sameas CONTENTS KEY.

Function: Used as a key necessary for calculating MAC of S-YMDhms.

Value: 0 to 0xFFFFFFFFFFFFFFFF

=MAC

Meaning: Forged copyright information check value

Function: Represents the value generated with S-YMDhms and CONTENTS KEY.

Value: 0 to 0xFFFFFFFFFFFFFFFF

=TRK-nnn

Meaning: SQN (sequence) number of ATRAC3 data file reproduced.

Function: Represents FNo of TRKINF.

Value: 1 to 400 (0x190)

-   -   When there is no track, this area is all 0.

=INF-S

Meaning: Additional information of memory card (for example, informationwith respect to photos, songs, guides, etc.)

Function: Represents variable length additional information with aheader. A plurality of types of additional information may be used. Eachof the types of additional information has an ID and a data size. Eachadditional information area including a header is composed of at least16 bytes and a multiple of 4 bytes. For details, see the followingsection.

Value: Refer to the section of “Data Structure of AdditionalInformation”.

=S-YMDhms (4 bytes) (Option)

Meaning: Year, month, day, hour, minute, and second recorded by therecorder/player with a reliable clock.

Function: Identifies the last recorded date and time. In this case ofEMD, this area is mandatory.

Value: bits 25 to 31: Year 0 to 99 (1980 to 2079)

bits 21 to 24: Month 0 to 12

bits 16 to 24: Day 0 to 31

bits 11 to 15: Hour 0 to 23

bits 05 to 10: Minute 0 to 59

bits 00 to 04: Second 0 to 29 (two second interval)

As the last slot of the reproduction management file, the sameBLKID-TL0, MCode, and REVISION as those in the header are written.

While data is being recorded to a memory card, it may be mistakenly oraccidentally detached or the power of the recorder/player may be turnedoff. When such an improper operation is performed, a defect should bedetected. As described above, the REVISION area is placed at thebeginning and end of each block. Whenever data is rewritten, the valueof the REVISION area is incremented. If a defect termination takes placein the middle of a block, the value of the REVISION area at thebeginning of the block does not match the value of the REVISION area atthe end of the block. Thus, such a defect termination can be detected.Since there are two REVISION areas, the abnormal termination can bedetected with a high probability. When an abnormal termination isdetected, an alarm such as an error message is generated.

In addition, since the fixed value BLKID-TL0 is written at the beginningof one block (16 KB), when the FAT is destroyed, the fixed value is usedas a reference for recovering data. In other words, with reference tothe fixed value, the type of the file can be determined. Since the fixedvalue BLKID-TL0 is redundantly written at the header and the end portionof each block, the reliability can be secured. Alternatively, the samereproduction management file can be redundantly recorded.

The data amount of an ATRAC3 data file is much larger than that of thetrack information management file. In addition, as will be describedlater, a block number BLOCK SERIAL is added to ATRAC3 data file.However, since a plurality of ATRAC3 files are recorded to the memorycard, to prevent them from become redundant, both CONNUM0 and BLOCKSERIAL are used. Otherwise, when the FAT is destroyed, it will bedifficult to recover the file. In other words, one ATRAC3 data file maybe composed of a plurality of blocks that are dispersed. To identifyblocks of the same file, CONNUM0 is used. In addition, to identify theorder of blocks in the ATRAC3 data file, BLOCK SERIAL is used.

Likewise, the maker code (Mcode) is redundantly recorded at thebeginning and the end of each block so as to identify the maker and themodel in such a case that a file has been improperly recorded in thestate that the FAT has not been destroyed.

FIG. 12C is a schematic diagram showing the structure of the additionalinformation data. The additional information is composed of thefollowing header and variable length data. The header has the followingareas.

=INF

Meaning: FIELD ID

Function: Represents the beginning of the additional information (fixedvalue).

Value: 0x69

=ID

Meaning: Additional information key code

Function: Represents the category of the additional information.

Value: 0 to 0xFF

=SIZE

Meaning: Size of individual additional information

Function: Represents the size of each type of additional information.Although the data size is not limited, it should be at least 16 bytesand a multiple of 4 bytes. The rest of the data should be filled withnull (0x00).

Value: 16 to 14784 (0x39C0)

=MCode

Meaning: MAKER CODE

Function: Identifies the maker and model of the recorder/player.

Value: High-order 10 bits (maker code), low-order 10 bits (machinecode).

=C+L

Meaning: Attribute of characters in data area starting from byte 12.

Function: Represents the character code and the language code as onebyte code.

Value: Same as SNC+L

=DATA

Meaning: Individual additional information

Function: Represents each type of additional information with variablelength data. Real data always starts from byte 12. The length (size) ofthe real data should be at least 4 bytes and a multiple of 4 bytes. Therest of the data area should be filled with null (0x00).

Value: Individually defined corresponding to the contents of each typeof additional information.

FIG. 13 is a table that correlates key code values (0 to 63 ofadditional information and types thereof. Key code values (0 to 31) areassigned to music character information. Key code values (32 to 63) areassigned to URLs (Uniform Resource Locator) (web information). The musiccharacter information and URL information contain character informationof the album title, the artist name, the CM, and so forth as additionalinformation.

FIG. 14 is a table that correlates key code values (64 to 127) ofadditional information and types thereof. Key code values (64 to 95) areassigned to paths/others. Key code values (96 to 127) are assigned tocontrol/numeric data. For example, ID=98 represents TOC-ID as additionalinformation. TOC-ID represents the first music program number, the lastmusic program number, the current program number, the total performanceduration, and the current music program duration corresponding to theTOC information of a CD (Compact Disc).

FIG. 15 is a table that correlates key code values (128 to 159) ofadditional information and types thereof. Key code values (128 to 159)are assigned to synchronous reproduction information. In FIG. 15, EMDstands for electronic music distribution.

Next, with reference to FIGS. 16A to 16E, real examples of additionalinformation will be described. As with FIG. 12C, FIG. 16A shows the datastructure of the additional information. In FIG. 16B, key code ID=3(artist name as additional information). SIZE=0x1C (28 bytes)representing that the data length of additional information includingthe header is 28 bytes; C+L representing that character code C=0x01(ASCII) and language code L=0x09 (English). Variable length data afterbyte 12 represents one byte data “SIMON & GRAFUNKEL” as artist name.Since the data length of the additional information should be a multipleof 4 bytes, the rest is filled with (0x00).

In FIG. 16C, key code ID=97 representing that ISRC (InternationalStandard Recording Code: Copyright code) as additional information.SIZE=0x14 (20 bytes) representing that the data length of the additionalinformation is 20 bytes. C=0x00 and L=0x00 representing that charactersand language have not been set. Thus, the data is binary code. Thevariable length data is eight-byte ISRC code representing copyrightinformation (nation, copyright owner, recorded year, and serial number).

In FIG. 16D, key code ID=is 97 representing recorded date and time asadditional information. SIZE=0x10 (16 bytes) representing that the datalength of the additional information is 16 bytes. C=0x00 andL=representing that characters and language have not been set. Thevariable length data is four-byte code (32 bit) representing therecorded date and time (year, month, day, hour, minute, second).

In FIG. 16E, key code ID=107 representing a reproduction log asadditional information. SIZE=0x10 (16 bytes) representing that the datalength of the additional information is 16 bytes. C=0x00 and L=0x00representing that characters and language have not been set. Thevariable length data is a four-byte code representing a reproduction log(year, month, day, hour, minute, second). When the recorder/player has areproduction log function, it records data of 16 bytes whenever itreproduces music data.

FIG. 17 is a schematic diagram showing a data arrangement of ATRAC3 datafile A3Dnnnn in the case that 1 SU is N bytes (for example, N=384bytes). FIG. 17 shows an attribute header (1 block) of a data file and amusic data file (1 block). FIG. 17 shows the first byte (0x0000 to0x7FF0) of each slot of the two blocks (16×2=32 kbytes). As shown inFIG. 18, the first 32 bytes of the attribute header are used as aheader; 256 bytes are used as a music program area NM1 (256 bytes); and512 bytes are used as a music program title area NM2 (512 bytes). Theheader of the attribute header contains the following areas.

=BLKID-HD0 (4 bytes)

Meaning: BLOCKID FIELD ID

Function: Identifies the top of an ATRA3 data file.

Value: Fixed value=“HD=0” (For example, 0x48442D30)

=MCode (2 bytes)

Meaning: MAKER CODE

Function: Identifies the maker and model of the recorder/player

Value: High-order 10 bits (maker code); low-order 6 bits (machine code)

=BLOCK SERIAL (4 bytes)

Meaning: Track serial number

Function: Starets from 0 and increments by 1. Even if a music program isedited, this value does not vary.

Value: 0 to 0xFFFFFFFF.

=N1C+L (2 bytes)

Meaning: Represents the attribute of data (NM1) of a track (musicprogram title).

Function: Represent the character code and language code of NM1 as onebyte code.

Value: Same as SN1C+L

N2C+L (2 bytes)

Meaning: Represents the attribute of data (NM2) of a track (musicprogram title).

Function: Represent the character code and language code of NM1 as onebyte code.

Value: Same as SN1C+L

=INFSIZE (2 bytes)

Meaning: Total size of additional information of current track.

Function: Represents the data size as a multiple of 16 bytes. When datais not recorded, this area should be all 0.

Value: 0x0000 to 0x3C6 (966)

=T-PRT (2 bytes)

Meaning: Number of total bytes

Function: Represents the number of parts that composes the currenttrack. Normally, the value of T-PRT is 1.

Value: 1 to 285 (645 dec).

=T-SU (4 bytes)

Meaning: Number of total SU.

Function: Represents the total number of SU in one track that isequivalent to the program performance duration.

Value: 0x01 to 0x001FFFFF

=INX (2 bytes) (Option)

Meaning: Relative position of INDEX

Function: Used as a pointer that represents the top of a representativeportion of a music program. The value of INX is designated with a valueof which the number of SU is divided by 4 as the current position of theprogram. This value of INX is equivalent to 4 times larger than thenumber of SU (around 93 msec).

Value: 0 to 0xFFFF (max, around 6084 sec)

=XT (2 bytes) (Option)

Meaning: Reproduction duration of INDEX

Function: Designates the reproduction duration designated by INX-nnnwith a value of which the number of SU is divided by 4. The value ofINDEX is equivalent to four times larger than the normal SU (around 93msec).

Value: 0x0000 (no setting); 0x01 to 0xFFFE (up to 6084 sec); 0xFFFF (upto end of music program)

Next, the music program title areas NM1 and NM2 will be described.

=NM1

Means: Character string of music program title

Function: Represents a music program title as one byte code (up to 256characters) (variable length). The title area should be completed withan end code (0x00). The size should be calculated from the end code.When data is not recorded, null (0x00) should be recorded from thebeginning (0x0020) of the area for at least one byte.

Value: Various character codes

=NM2

Means: Character string of music program title

Function: Represents a music program title as two byte code (up to 512characters) (variable length). The title area should be completed withan end code (0x00). The size should be calculated from the end code.When data is not recorded, null (0x100) should be recorded from thebeginning (0x0120) of the area for at least two bytes.

Value: Various character codes

Data of 80 bytes starting from the fixed position (0x320) of theattribute header is referred to as track information area TRKINF. Thisarea is mainly used to totally manage the security information and copycontrol information. FIG. 19 shows a part of TRKINF. The area TRKINFcontains the following areas.

=CONTENTS KEY (8 bytes)

Meaning: Value for each music program. The value of CONTENTS KEY isprotected in the security block of the memory card and then stored.

Function: Used as a key for reproducing a music program. It is used tocalculate the value of MAC.

Value: 0 to 0xFFFFFFFFFFFFFFFF

=MAC (8 bytes)

Meaning: Forged copyright information check value Function: Representsthe value generated with a plurality of values of TRKINF includingcontents cumulation numbers and a secret sequence number.

The secret sequence number is a sequence number recorded in the secretarea of the memory card. A non-copyright protection type recorder cannotread data from the secret area of the memory card. On the other hand, acopyright protection type recorder and a computer that operates with aprogram that can read data from a memory card can access the secretarea.

=A (1 byte)

Meaning: Attribute of part.

Function: Represents the information of such as compression mode of apart.

Value: The details will be described in the following (see FIGS. 19 and20).

Next, the value of the area A will be described. In the followingdescription, monaural mode (N=0 or 1) is defined as a special joint modeof which bit 7=1, sub signal=0, main signal=(L+R). A non-copyrightprotection type player may ignore information of bits 2 and 1.

Bit 0 of the area A represents information of emphasis on/off state. Bit1 of the area A represents information of reproduction skip or normalreproduction. Bit 2 of the area A represents information of data typesuch as audio data, FAX data, or the like. Bit 3 of the area A isundefined. By a combination of bits 4, 5, and 6, mode information ofATRAC3 is defined as shown in FIG. 20. In other words, N is a mode valueof 3 bits. For five types of modes that are monaural (N=0 or 1), LP(N=2), SP (N=4), EX (N=5), and HQ (N=7), record duration (64 MB memorycard only), data transmission rate, and the number of SU per block arelisted. The number of bytes of 1 SU depends on each mode. The number ofbytes of 1 SU in the monaural mode is 136 bytes. The number of bytes of1 SU in the LP mode is 192 bytes. The number of bytes of 1 SU in the SPmode is 304 bytes. The number of bytes of 1 SU in the EX mode is 384bytes. The number of bytes of 1 SU in the HQ mode is 512 bytes. Bit 7 ofthe area A represents ATRAC3 modes (0: Dual, 1: JOint).

For example, an example of which a 64 MB memory card is used in the SPmode will be described. A 64-MB memory card has 3968 blocks. In the SPmode, since 1 SU is 304 bytes, one block has 53 SU. 1 SU is equivalentto (1024/44100) seconds. Thus, one block is(1024/44100)×53×(3968−10)=4863 seconds=81 minutes. The transmission rateis (44100/1024)×304×8=104737 bps.

=LT (one byte)

Meaning: Reproduction restriction flag (bits 7 and 6) and securitypartition (bits 5 to 0).

Function: Represents a restriction of the current track.

Value: bit 7: 0=no restriction, 1=restriction

-   -   bit 6: 0 not expired, 1=expired    -   bits 5 to 0: security partition (reproduction        -   prohibited other than 0)

=FNo (2 bytes)

Meaning: File number.

Function: Represents the initially recorded track number that designatesthe position of the MAC calculation value recorded in the secret area ofthe memory card.

Value: 1 to 0x190 (400)

=MG(D) SERIAL-nnn (16 bytes)

Meaning: Represents the serial number of the security block (security IC20) of the recorder/player.

Function: Unique value for each recorder/player

Value: 0 to 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

=CONNUM (4 bytes)

Meaning: Contents cumulation number

Function: Represents a unique value cumulated for each music program.The value is managed by the security block of the recorder/player. Theupper limit of the value is 2³² that is 4,200,000,000. Used to identifya recorded program.

Value: 0 to 0xFFFFFFFF

YMDhms-S (4 bytes) (Option)

Meaning: Reproduction start date and time of track with reproductionrestriction

Function: Represents the date and time at which data reproduction ispermitted with EMD.

Value: Same as the notation of date and time of other areas

=YMDhms-E (4 bytes) (Option)

Meaning: Reproduction end date and time of track with reproductionrestriction

Function: Represents the date and time at which data reproduction isexpired with EMD.

Value: Same as the notation of date and time of other areas

=MT (1 byte) (Option)

Meaning: Maximum value of number of permitted reproduction times

Function: Represents the maximum number of reproduction times designatedby EMD.

Value: 1 to 0xFF. When not used, the value of the area MT is 00.

=CT (1 byte) (Option)

Meaning: Number of reproduction times

Function: Represents the number of reproduction times in the number ofpermitted reproduction times. Whenever data is reproduced, the value ofthe area CT is decremented.

Value: 0x00 to 0xFF. When not used, the value of the area CT is 0x00.When bit 7 of the area LT is 1 and the value of the area CT is 00, datais prohibited from being reproduced.

=CC (1 byte)

Meaning: COPY CONTROL

Function: Controls the copy operation.

Value: bits 6 and 7 represent copy control information bits 4 and 5represent copy control information of a high speed digital copyoperation bits 2 and 3 represent a security block authentication levelbits 0 and 1 are undefined.

Example of CC:

-   -   (bits 7 and 6)    -   11: Unlimited copy operation permitted    -   01: copy prohibited    -   00: one time copy operation permitted (bits 3 and 2)    -   00: analog/digital input recording        -   MG authentication level is 0.

When digital record operation using data from a CD is performed, (bits 7and 6): 00 and (bits 3 and 2): 00.

=CN (1 byte) (Option)

Meaning: Number of permitted copy times in high speed serial copymanagement system

Function: Extends the copy permission with the number of copy times, notlimited to one time copy permission and copy free permission. Valid onlyin first copy generation. The value of the area CN is decrementedwhenever the copy operation is performed.

Value″

-   -   00: Copy prohibited    -   01 to 0xFE: Number of times    -   0xFF: Unlimited copy times

The track information area TRKINF is followed by a 24-byte partmanagement information area (PRTINF) starting from 0x0370. When onetrack is composed of a plurality of parts, the values of areas PRTINF ofthe individual parts are successively arranged on the time axis. FIG. 22shows a part of the area PRTINF. Next, areas in the area PRTINF will bedescribed in the order of the arrangement.

=PRTSIZE (4 bytes)

Meaning: Part size

Function: Represents the size of a part. Cluster: 2 bytes (highestposition), start SU: 1 byte (upper), end SU: 1 byte (lowest position).

Value: cluster: 1 to 0x1F40 (8000)

-   -   start SU: 0 to 0xA0 (160)    -   end SU: 0 to 0xA0 (16) (Note that SU starts from 0.)

=PRTKEY (8 bytes)

Meaning: Part encrypting value

Function: Encrypts a part. Initial value=0. Note that edit rules shouldbe applied.

Value: 0 to 0xFFFFFFFFFFFFFFFF

=CONNUM0 (4 bytes)

Meaning: Initially generated contents cumulation number key

Function: Uniquely designates an ID of contents.

Value: Same value as the value of the contents cumulation number initialvalue key

As shown in FIG. 17, the attribute header of an ATRAC3 data filecontains additional information INF. The additional information is thesame as the additional information INF-S (see FIGS. 11 and 12B) of thereproduction management file except that the start position is notfixed. The last byte position (a multiple of four bytes) at the end ofone or a plurality of parts is followed by data of the additionalinformation INF.

=INF

Meaning: Additional information with respect to track

Function: Represents variable length additional information with aheader. A plurality of different types of additional information may bearranged. Each of additional information areas has an ID and a datasize. Each additional information area is composed of at least 16 bytesand a multiple of 4 bytes.

Value: Same as additional information INF-S of reproduction managementfile

The above-described attribute header is followed by data of each blockof an ATRAC3 data file. As shown in FIG. 23, a header is added for eachblock. Next, data of each block will be described.

=BLKID-A3D (4 bytes)

Meaning: BLOCKID FILE ID

Function: Identifies the top of ATRAC3 data.

Value: Fixed value=“A3D” (for example, 0x41334420)

=MCode (2 bytes)

Meaning: MAKER CODE

Function: Identifies the maker and model of the recorder/player

Value: High-order 10 bits (maker code); low-order 6 bits (model code)

=CONNUMO (4 bytes)

Meaning: Cumulated number of initially created contents

Function: Designates a unique ID for contents. Even if the contents areedited, the value of the area CONNUMO is not changed.

Value: Same as the contents cumulation number initial key

=BLOCK SERIAL (4 bytes)

Meaning: Serial number assigned to each

Function: Starts from 0 and increments by 1. Even if the contents areedited, the value of the area BLOCK SERIAL is not changed.

Value: 0 to 0xFFFFFFFF

=BLOCK-SEED (8 bytes)

Meaning: Key for encrypting one block

Function: The beginning of the block is a random number generated by thesecurity block of the recorder/player. The random number is followed bya value incremented by 1. When the value of the area BLOCK-SEED is lost,since sound is not generated for around one second equivalent to oneblock, the same data is written to the header and the end of the block.Even if the contents are edited, the value of the area BLOCK-SEED is notchanged.

Value: Initially 8-bit random number

=INITIALIZATION VECTOR (8 bytes)

Meaning: Value necessary for encrypting/decrypting ATRAC3 data

Function: Represents an initial value necessary for encrypting anddecrypting ATRAC3 data for each block. A block starts from 0. The nextblock starts from the last encrypted 8-bit value at the last SU. When ablock is divided, the last eight bytes just before the start SU is used.Even if the contents are edited, the value of the area INITIALIZATIONVECTOR is not changed.

Value: 0 to 0xFFFFFFFFFFFFFFFF

=SU-nnn

Meaning: Data of sound unit

Function: Represents data compressed from 1024 samples. The number ofbytes of output data depends on the compression mode. Even if thecontents are edited, the value of the area SU-nnn is not changed. Forexample in the SP mode, N=384 bytes.

Value: Data value of ATRAC3

In FIG. 17, since N=384, 42 SU are written to one block. The first twoslots (4 bytes) of one block are used as a header. In the last slot (twobytes), the areas BLKID-A3D, MCode, CONNUM0, and BLOCK SERIAL areredundantly written. Thus, M bytes of the remaining area of one block is(16,384−384×42−16×3=208) bytes. As described above, the eight-byte areaBLOCK SEED is redundantly recorded.

When the FAT area is destroyed, all blocks of the flash memory aresearched. It is determined whether the value of the area ID BLKID at thebeginning of each block is TL0, HD0, or A3D. As shown in FIGS. 24A to24C, at step SP1, it is determined whether or not the value of the areaID BLKID at the beginning of the top block is BLKID-TL0. When thedetermined result at step SP1 is No, the flow advances to step SP2. Atstep SP2, the block number is incremented. Thereafter, at step SP3, itis determined whether or not the last block has been searched.

When the determined result at step SP3 is No, the flow returns to stepSP1.

When the determined result at step SP1 is Yes, the flow advances to stepSP4. At step SP4, it is determined that the searched block is thereproduction management file PBLIST. Thereafter, the flow advances, ostep SP5. At step SP5, the number of total tracks T-TRK in thereproduction management file PBLIST is stored as N to the register. Forexample, when the memory has stored 10 ATRAC3 data files (10 musicprograms), 10 has been stored in T-TRK.

Next, with reference to the value of the number of total tracks T-TRK,TRK-001 to TRK-400 of blocks are successively referenced. In thisexample, since 10 music programs have been recorded, TRK-001 to TRK-010of blocks are referenced. Since a file number FNO has been recorded inTRK-XXX (where X=1 to 400) at step SP7, a table that correlates thetrack number TRK-XXX and the file number FNO is stored to the memory.Next, at step SP8, N stored in the register is decremented. A loop ofsteps SP6, SP7, and SP8 is repeated until N becomes 0 at step SP9.

When the determined result at step SP9 is Yes, the flow advances to stepSP10. At step SP10, the pointer is reset to the top block. The searchingprocess is repeated from the top block. Thereafter, the flow advances tostep SP11. At step SP11, it is determined whether or not the value ofthe area ID BLKID of the top block is BLKID-HD0. When the determinedresult at step SP11 is No, the flow advances to step SP12. At step SP12,the block number is incremented. At step SP13, it is determined whetheror not the last block has been searched.

When the determined result at step SP13 is No, the flow returns to stepSP11. The searching process is repeated until the determined result atstep SP11 becomes Yes.

When the determined result at step SP11 is Yes, the flow advances tostep SP14. At step SP14, it is determined that the block is theattribute header (see FIG. 8) (0x0000 to 0x03FFF shown in FIG. 18) atthe beginning of the ATRAC3 data file.

Next, at step SP15, with reference to the file number FNO, the sequencenumber BLOCK SERIAL of the same ATRAC data file, and the contentscumulation number key CONNUM0 contained in the attribute header, theyare stored to the memory. When 10 ATRAC3 data files have been recorded,since there are 10 blocks of which the value of the area ID BLKID of thetop block is BLKID-TL0, the searching process is continued until 10blocks are searched.

When the determined result at step SP13 is Yes, the flow advances tostep SP16. At step SP16, the pointer is reset to the top block. Thesearching process is repeated from the top block.

Thereafter, the flow advances to step SP17. At step SP17, it isdetermined whether or not the value of the area ID BLKID of the topblock is BLKID-A3D.

When the determined result at step SP17 is No, the flow advances to stepSP18. At step SP18, the block number is incremented. Thereafter, at stepSP18′, it is determined whether or not the last block has been searched.When the determined result at step SP18′ is No, the flow returns to stepSP17.

When the determined result at step SP17 is Yes, the flow advances tostep SP19. At step SP19, it is determined that the block contains ATRAC3data. Thereafter, the flow advances to step SP20. At step SP20, withreference to the serial number BLOCK SERIAL recorded in the ATRAC3 datablock and the contents cumulation number key CONNUM0, they are stored tothe memory.

In the same ATRAC3 data file, the common number is assigned as thecontents cumulation number key CONNUM0. In other words, when one ATRAC3data file is composed of 10 blocks, a common number is assigned to allthe values of the areas CONNUM0.

In addition, when one ATRAC3 data is composed of 10 blocks, serialnumbers 1 to 0 are assigned to the values of the areas BLOCK SERIALs ofthe 10 blocks.

Corresponding to the values of the areas CONNUM0 and BLOCK SERIAL, it isdetermined whether the current block composes the same contents and thereproduction order of the current block in the same contents (namely,the connection sequence).

When 10 ATRAC3 data files (namely, 10 music programs) have been recordedand each of the ATRAC3data files is composed of 10 blocks, there are 100data blocks.

With reference to the values of the areas CONNUM0 and BLOCK SERIAL, thereproduction order of music programs of 100 data blocks and theconnection order thereof can be obtained.

When the determined result at step SP19 is Yes, all the blocks have beensearched for the reproduction management file, the ATRAC3 data file, andthe attribute file. Thus, at step SP21, based on the values of the areasCONNUM0, BLOCK SERIAL, FNO, and TRK-X in the order of block numbers ofthe blocks stored in the memory, the file connection state is obtained.

After the connection state is obtained, the FAT may be generated in afree area of the memory

Next, a management file according to a second embodiment of the presentinvention will be described. FIG. 25 shows the file structure accordingto the second embodiment of the present invention. Referring to FIG. 25,a music directory contains a track information management fileTRKLIST.MSF (hereinafter, referred to as TRKLIST), a backup trackinformation management file TRKLISTB.MSF (hereinafter, referred to asTRKLISTB), an additional information file INFLIST.MSF (that contains anartist name, an ISRC code, a time stamp, a still picture data, and soforth (this file is referred to as INFIST)), an ATRAC3 data fileA3Dnnnn.MSF (hereinafter, referred to as A3nnnn). The file TRKLISTcontains two areas NAME1 and NAME2. The area NAME1 is an area thatcontains the memory card name and the program name (for one byte codecorresponding to ASCII/8859-1 character code). The area NAME2 is an areathat contains the memory card name and the program name (for two bytecode corresponding to MS-JIS/Hankul/Chinese code).

FIG. 26 shows the relation between the track information management fileTRKLIST, the areas NAME1 and NAME2, and the ATRAC3 data file A3Dnnnn.The file TRKLIST is a fixed length file of 64 kbytes (=16 k×4). An areaof 32 kbytes of the file is used for managing tracks. The remaining areaof 32 kbytes is used to contain the areas NAME1 and NAME2. Although theareas NAME1 and NAME2 for program names may be provided as a differentfile as the track information management file, in a system having asmall storage capacity, it is convenient to totally manage the trackinformation management file and program name files.

The track information area TRKINF-nnnn and part information areaPRTINF-nnnn of the track information management file TRKLIST are used tomanage the data file A3Dnnnn and the additional information INFLIST.Only the ATRAC3 data file A3Dnnnn is encrypted. In FIG. 26, the datalength in the horizontal direction is 16 bytes (0 to F). A hexadecimalnumber in the vertical direction represents the value at the beginningof the current line.

According to the second embodiment, three files that are the trackmanagement file TRKLIST (including a program title file), the additionalinformation management file INFLIST, and the data file A3Dnnnn are used.According to the first embodiment (see FIGS. 7, 8, and 9), two filesthat are the reproduction management file PBLIST for managing all thememory card and the data file ATRAC3 for storing programs are used.

Next, the data structure according to the second embodiment will bedescribed. For simplicity, in the data structure according to the secondembodiment, the description of similar portions to those of the firstembodiment is omitted.

FIG. 27 shows the detailed structure of the track information managementfile TRKLIST. In the track information management file TRKLIST, onecluster (block) is composed of 16 kbytes. The size and data of the fileTRKLISTB are the same as those of the backup file TRKLISTB. The first 32bytes of the track information management file are used as a header. Aswith the header of the reproduction management file PBLIST, the headerof the file TRKLIST contains a BLKID-TL0/TL1 (backup file ID) area (4bytes), an area T-TRK (2 bytes) for the number of total tracks, a makercode area MCode (2 bytes), an area REVISION (4 bytes) for the number ofTRKLIST rewrite times, and an area S-YMDhms (4 bytes) (option) forupdate date and time data. The meanings and functions of these dataareas are the same as those of the first embodiment. In addition, thefile TRKLIST contains the following areas.

=YMDhms (4 bytes)

Represents the last update date (year, month, day) of the file TRKLIST.

=N1 (1 byte) (Option)

Represents the sequential number of the memory card (numerator side).When one memory card is used, the value of the area N1 is 0x01.

=N2 (1 byte) (Option)

Represents the sequential number of the memory card (denominator side).When one memory card is used, the value of the area N2 is 0x01.

=MSID (2 bytes) (Option)

Represents the ID of a memory card. When a plurality of memory cards isused, the value of the area MSID of each memory card is the same(T.B.D.). (T.B.D. (to be defined) represents that this value may bedefined in future).

=S-TRK (2 bytes).

Represents a special track (T.B.D.). Normally, the value of the areaS-TRK is 0x0000.

=PASS (2 bytes) (Option)

Represents a password (T.B.D.).

=APP (2 bytes) (Option)

Represents the definition of a reproduction application (T.B.D.)(normally, the value of the area APP is 0x0000).

=INF-S (2 bytes) (Option)

Represents the additional information pointer of the entire memory card.When there is no additional information, the value of the area INF-S is0x00.

The last 16 bytes of the file TRKLIST are used for an area BLKID-TL0, anarea MCode, and an area REVISION that are the same as those of theheader. The backup file TRKLISTB contains the above-described header. Inthis case, the header contains an area BLKID-TL1, an area MCode, and anarea REVISION.

The header is followed by a track information area TRKINF forinformation with respect to each track and a part information areaPRTINF for information with respect to each part of tracks (musicprograms). FIG. 27 shows the areas preceded by the area TRKLIST. Thelower portion of the area TRKLISTB shows the detailed structure of theseareas. In. FIG. 27, a hatched area represents an unused area.

The track information area TRKINF-nnn and the part information areaPRTINF-nnn contain areas of an ATRAC3 data file. In other words, thetrack information area TRKINF-nnn and the part information areaPRTINF-nnn each contain a reproduction restriction flag area LT (1byte), a contents key area CONTENTS KEY (8 bytes), a recorder/playersecurity block serial number area MG(D). SERIAL (16 bytes), an area XT(2 bytes) (option) for representing a feature portion of a musicprogram, an area INX (2 bytes) (option), an area YMDhms-S (4 bytes)(option), an area YMDhms-E (4 bytes) (option), an area MT (1 byte)(option), an area CT (1 byte) (option), an area CC (1 byte) (option), anarea CN (1 byte) (option) (these areas YMDhms-S, YMDhms-E, MT, CT, CC,and CN are used for reproduction restriction information and copycontrol information), an area A (1 byte) for part attribute, a part sizearea PRTSIZE (4 bytes), a part key area PRTKEY (8 bytes), and a contentscumulation number area CONNUM (4 bytes). The meanings, functions, andvalues of these areas are the same as those of the first embodiment. Inaddition, the track information area TRKINF-nnn and the part informationarea PRTINF-nnn each contain the following areas.

=T0 (1 byte)

Fixed value (T0=0x74)

=INF-nnn (Option) (2 bytes)

Represents the additional information pointer (0 to 409) of each track.00: music program without additional information.

=FNM-nnn (4 bytes)

Represents the file number (0x0000 to 0xFFFF) of an ATRK3 data file.

The number nnnn (in ASCII) of the ATRAC3 data file name (A3Dnnnn) isconverted into 0xnnnnn.

=APP_CTL (4 bytes) (Option)

Represents an application parameter (T.B.D.) (Normally, the value of thearea APP_CTL is 0x0000).

=P-nnn (2 bytes)

Represents the number of parts (1 to 2039) that compose a music program.This area corresponds to the above-described area T-PART.

=PR (1 byte)

Fixed value (PR=0x50).

Next, the areas NAME1 (for one byte code) and NAME2 (for two byte code)for managing names will be described. FIG. 28 shows the detailedstructure of the area NAME1 (for one byte code area). Each of the areasNAME1 and NAME2 (that will be described later) is segmented with eightbytes. Thus, their one slot is composed of eight bytes. At 0x8000 thatis the beginning of each of these areas, a header is placed. The headeris followed by a pointer and a name. The last slot of the area NAME1contains the same areas as the header.

=BLKID-NM1 (4 bytes)

Represents the contents of a block (fixed value) (NM1=0x4E4D2D31).

=PNM1-nnn (4 bytes). (Option)

Represents the pointer to the area NM1 (for one byte code).

=PNM1-S

Represents the pointer to a name representing a memory card.

nnn (=1 to 408) represents the pointer to a music program title.

The pointer represents the start position (2 bytes) of the block, thecharacter code type (2 bits), and the data size (14 bits).

=NM1-nnn (Option)

Represents the memory card name and music program title for one bytecode (variable length). An end code (0x000) is written at the end of thearea.

FIG. 29 shows the detailed data structure of the area NAME2 (for twobyte code). At 0x8000 that is the beginning of the area, a header isplaced. The header is followed by a pointer and a name. The last slot ofthe area NAME2 contains the same areas as the header.

=BLKID-NM2 (4 bytes)

Represents the contents of a block (fixed value) (NM2=0x4E4D2D32).

=PNM2-nnn (4 bytes) (Option)

Represents the pointer to the area NM2 (for two byte code).

PNM2-S represents the pointer to the name representing the memory card.nnn (=1 to 408) represents the pointer to a music program title.

The pointer represents the start position (2 bytes) of the block, thecharacter code type (2 bits), and the data size (14 bits).

=NM2-nnn (Option)

Represents the memory card name and music program title for two bytecode (variable). An end code (0x0000) is written at the end of the area.

FIG. 30 shows the data arrangement (for one block) of the ATRAC3 datafile A3Dnnnn in the case that 1 SU is composed of N bytes. In this file,one slot is composed of eight bytes. FIG. 30 shows the values of the topportion (0x0000 to 0x3FF8) of each slot. The first four slots of thefile are used for a header. As with the data block preceded by theattribute header of the data file (see FIG. 17) of the first example, aheader is placed. The header contains an area BLKID-A3D (4 bytes), amaker code area MCode (2 bytes), an area. BLOCK SEED (8 bytes) necessaryfor encrypting process, an area CONNUM0 (4 bytes) for the initialcontents cumulation number, a serial number area BLOCK SERIAL (4 bytes)for each track, and an area INITIALIZATION VECTOR (8 bytes) necessaryfor encrypting/decrypting process. The second last slot of the blockredundantly contains an area BLOCK SEED. The last slot contains areasBLKID-A3D and MCode. As with the first embodiment, the header isfollowed by the sound unit data SU-nnnn.

FIG. 31 shows the detailed data structure of the additional informationmanagement file INFLIST that contains additional information. In thesecond embodiment, at the beginning (0x0000) of the file INFLIST, thefollowing header is placed. The header is followed by the followingpointer and areas.

=BLKID-INF (4 bytes)

Represents the contents of the block (fixed value) (INF=0x494E464F)

=T-DAT (2 blocks)

Represents the number of total data areas (0 to 409).

=MCode (2 bytes)

Represents the maker code of the recorder/player

=YMDhms (4 bytes)

Represents the record updated date and time.

=INF-nnnn (4 bytes)

Represents the pointer to the area DATA of the additional information(variable length, as 2 bytes (slot) at a time). The start position isrepresented with the high order 16 bits (0000 to FFFF).

=DataSlot-0000 (0x0800)

Represents the offset value from the beginning (as a slot at a time).

The data size is represented with low, order 16 bits (0001 to 7FFF). Adisable flag is set at the most significant bit. MSB=0 (Enable), MSB=1(Disable).

The data size represents the total data amount of the music program.

(The data starts from the beginning of each slot. (The non-data area ofthe slot is filled with 00.)

The first INF represents a pointer to additional information of theentire album (normally, INF-409).

FIG. 32 shows the structure of additional information. An 8-byte headeris placed at the beginning of one additional information data area. Thestructure of the additional information is the same as that of the firstembodiment (see FIG. 12C). In other words, the additional informationcontains an area IN (2 bytes) as an ID, an area key code ID (1 byte), anarea SIZE (2 bytes) that represents the size of each additionalinformation area, and a maker code area MCode (2 bytes). In addition,the additional information contains an area SID (1 byte) as a sub ID.

According to the second embodiment of the present invention, in additionto the file system defined as a format of the memory card, the trackinformation management file TRKLIST for music data is used. Thus, evenif the FAT is destroyed, the file can be recovered. FIG. 33 shows a flowof a file recovering process. To recover the file, a computer thatoperates with a file recovery program and that can access the memorycard and a storing device (hard disk, RAM, or the like) connected to thecomputer are used. The computer has a function equivalent to the DSP30.Next, a file recovering process using the track management file TRKLISTwill be described.

All blocks of the flash memory whose FAT has been destroyed are searchedfor TL-0 as the value (BLKID) at the top position of each block. Inaddition, all the blocks are searched for NM-1 as the value (BLKID) atthe top position of each block. Thereafter, all the blocks are searchedfor NM-2 as the value (BLKID) at the top position of each block. All thecontents of the four blocks (track information management file) arestored to for example a hard disk by the recovery computer.

The number of total tracks is obtained from data after the fourth byteof the track information management file. The 20-th byte of the trackinformation area TRKINF-001, the value of the area CONNUM-001 of thefirst music program, and the value of the next area P-001 are obtained.The number of parts is obtained with the value of the area P-001. Thevalues of the areas PRTSIZE of all parts of the track 1 of the areaPRTINF is obtained. The number of total blocks (clusters) n iscalculated and obtained.

After the track information management file is obtained, the flowadvances to step 102. At step 102, a voice data file (ATRAC3 data file)is searched. All blocks of other than the management file is searchedfrom the flash memory. Blocks whose top value (BLKID) is A3D arecollected.

A block of which the value of the area CONNUM0 at the 16-th byte ofA3Dnnnn is the same as that of the area CONNUM-001 of the first musicprogram of the track information management file and of which the valueof the area BLOCK SERIAL that starts from 20-th byte is 0 is searched.After the first block is obtained, a block (cluster) with the same valueof the area CONNUM value as the first block and of which the value ofBLOCK SERIAL is incremented by 1 (1=0+1) is searched. After the secondblock is obtained, a block with the same value of the area CONNUM0 asthe second block and of which the value of the area BLOCK SERIAL isincremented by 1 (2=1+1) is searched.

By repeating the process, the ATRC3 data file is searched until n blocks(clusters) of the track 1 are obtained. When all the blocks (clusters)are obtained, they are successively stored to the hard disk.

The same process for the track 1 is performed for the track 2. In otherwords, a block of which the value of the area CONNUM0 is the same asthat of the area CONNUM-002 of the first music program of the trackinformation management file and of which the value of the area BLOCKSERIAL that starts at the 20-th byte is searched. Thereafter, in thesame manner as the track 1, the ATRAC3 data file is searched until thelast block (cluster) n′ is detected. After all blocks (clusters) areobtained, they are successively stored to the hard disk.

By repeating the above-described process for all tracks (the number oftracks: m); all the ATRAC3 data is stored to the hard disk controlled bythe recovering computer.

At step 103, the memory card whose the FAT has been destroyed isre-initialized and then the FAT is reconstructed. A predetermineddirectory is formed in the memory card. Thereafter, the trackinformation management file and the ATRAC3 data file for m tracks arecopied from the hard disk to the memory card. Thus, the recovery processis finished.

In the management file and data file, important parameters (inparticular, codes in headers) may be recorded triply rather than doubly.When data is redundantly recorded, the same data may be recorded at anypositions as long as they are apart from each other for one, page ormore.

According to the present invention, the abnormality of a data file(ATRAC3 file) recorded in a memory card is detected. Next, withreference to FIGS. 25 to 32, a circuit block that detects theabnormality of data will be described in detail.

As is clear from FIG. 20, the compression rate expected for conventionalmemory cards is around ⅛ to 1/43. In the case of 1024 samples/channelused for ATRAC3, the SU data amount (hereinafter referred to as SUvalue) as the data unit of the compressing process is in the range from256 bytes to 48 bytes.

Each block contains 50 SU. According to the embodiment of the presentinvention, by detecting a particular fixed value of one byte that is setto SU at the beginning of one block of decrypted data, it can bedetermined whether or not the audio data has been correctly encrypted.For example, the determination can be performed at intervals of onesecond. When abnormally reproduced data is detected, it is quickly mutedand/or a message that represents the abnormality is displayed. In therecorder shown in FIG. 1, the D/A converter 18 performs the mutingprocess so as to prevent abnormally reproduced output data from beinggenerated. Alternatively, when abnormally reproduced output data isdetected, the decompressing process may be prohibited.

Next, with reference to a block diagram shown in FIG. 34, the embodimentof the present invention in the case that data is recorded will bedescribed. As shown in FIG. 1, the audio encoder/decoder IC 10 suppliesaudio data that has been compressed corresponding to ATRAC3 to thesecurity IC 20. In FIG. 34, ATRAC3 compressed audio data is suppliedfrom an audio encoder 71 to a shift register 74 of a detecting portion73. The shift register 74 supplies the audio data to an encrypter 77. Asan example, a serial signal shown in FIG. 35 is supplied from the audioencoder 71 to the shift register 74. The timing at which the compressedaudio data is output from the audio encoder 71 to the shift register 74is controlled by a byte counter 72. In addition, the first read block ispre-set to the byte counter 72.

One block contains around 50 SU. When the first one byte of the first SUis stored to the shift register 74, a match detecting circuit 75determines whether or not the high order six bits of the first byte othe first SU of the block matches a fixed value VF1 (namely, 101000).The match detecting circuit 75 outputs the determined result Sc1. Insuch a manner, the detecting portion 73 determines whether or not thefixed value VF1 has been set to the first byte of one SU of ATRAC3 data.The encrypter 77 encrypts the supplied audio data with a key 78. Thedata encrypted by the encrypter 77 is written to a memory card 40. Inaddition, the data encrypted by the encrypter 77 is supplied to adecrypter 81.

The decrypter 81 decrypts encrypted data with a key 82 that is the sameas the key 78. Thus, the encrypted data is converted into a serialsignal shown in FIG. 35. The serial signal that is output from thedecrypter 81 is supplied to a shift register 85 of a detecting portion84. The timing at which the serial data is output from the decrypter 81to the shift register 85 is controlled by a byte counter 83. The firstread block is pre-set to the byte counter 83. The first one byte of thefirst one of 50 SU contained in one block is stored to the shiftregister 85. A match detecting circuit 86 determines whether or not thehigh order six bits of the one byte matches a fixed value VF2 (namely,101000). The match detecting circuit 86 outputs the determined resultSc2.

The determined result Sc1 that is output from the match detectingcircuit 75 is ANDed with the determined result Sc2 that is output fromthe match detecting circuit 86. In other words, when the high order sixbits of one byte stored in the shift register 74 matches the fixed valueVF1 and the high order six bits of one byte stored in the shift register85 matches the fixed value VF2 as the determined results of the matchdetecting circuits 75 and 86, a status that represents that the headeris OK is output. Otherwise, the reproduced audio data is muted. Whenaudio data is recorded, an alarm is issued. Alternatively, the system isreset and then it is determined whether reproduced output data becomesnormal.

Actually, it is difficult to set the fixed values VF1 and VF2 atintervals of for example 50 SU. Thus, the fixed values VF1 and VF2 areset to all SU. Only parts of 50 SU are extracted. When the fixed valuesVF1 and VF2 cannot be detected, an error flag is placed.

When the fixed values are set to all SU, abnormalities due to such as adifferent compression mode and a phase deviation of LR channels can bealso detected. In reality, as shown in FIG. 21, according to theembodiment of the present invention, there are two compression modesthat are Dual mode and Joint mode. In addition, there is monaural mode.Thus, there are a total of three recording methods.

One byte of the header is defined as follows.

101000-00: Dual (L)

101000-01: Dual (R)

101000-10: Joint

101000-11: Monaural

The match detecting circuit 75 or 86 determines whether or not the highorder six bits of one byte stored in the shift register 74 or 85 matchesthe fixed value VF1 or VF2. The low order two bits of one byte stored inthe shift register 74 or 85 define recording methods. Thus, both theabnormality of audio data and the compression mode can be detected atthe same time. In addition, since the compression mode is detected, aconfusion of which different compression modes are combined can beprevented.

Next, with reference to FIG. 36, a process for reproducing encrypteddata recorded in a memory card 40 will be described. For simplicity, inFIG. 36, similar functional blocks to those shown in FIG. 34 are denotedby similar reference numerals and their description is omitted.Encrypted data that is read from the memory card 40 is supplied to adecrypting circuit 81. A detecting portion 84 detects abnormalreproduced output audio data. When the reproduced output data isabnormal as the detected result of the detecting portion 84, theabnormally reproduced output data is immediately muted. As descriedabove, a muting signal is supplied to a D/A converter 18. Data that isoutput from the shift register 85 is supplied to an audio decoder 88.The audio decoder 88 reproduces the supplied data.

As a real example of the encrypting process performed by the encrypter77, CBC (Cipher Block Chaining) mode that is ont of four modes definedfor DES will be described. When the CBC mode is used, except for thefirst block of the track, eight bytes of the last SU of each precedingblock is stored. After data is encoded, it is decoded so as to determinewhether the fixed value at the beginning of the next block can bereproduced every second block (at intervals of around 1 second).

In the CBC mode, the first eight bytes P1 of the first SU of the firstblock of the track are exclusive-ORed with an initialization vector INV.The resultant data is encrypted with a key K. Thus, the followingrelation is satisfied.DES(P1(+)INV, K)=C1where DES: symbol of encrypting process, Pi: plane data, Ci: encrypteddata, K: key, and (+): symbol of exclusive-OR operation.

To encrypt other than the first block of the track, the immediatelyencrypted output data (encrypted data) C1 is required. The next eightbytes are encrypted as follows.DES(P2(+)C1, K)=C2

DES is performed every eight bytes. Thus, to encrypt the first eightbytes (beginning data) of the block, the last eight bytes (precedingdata) that have been encrypted of the preceding SU are required. Thus,the encrypter 77 requires a temporary storage memory that stores thebeginning data and the preceding data.

The decrypter 81 decrypts the encrypted data. Thus, the followingrelation is satisfied.IDES(C1, K)(+)INV=P1(+)INV(+)INV=P1where IDES: decrypting process

To decrypt other than the first block of the track, the precedingencrypted data C1 is required. Thus, the next eight bytes are decryptedas follows.IDES(C2, K)(+)C1=P2(+)C1(+)C1=P2

As with the encrypting process, IDES is performed every eight bytes.Thus, to decrypt eight bytes at the beginning (beginning data) ofencrypted data of a block, the last eight bytes (preceding data) ofencrypted data of the preceding SU of the block is required. Thus, thedecrypter 81 requires a temporary storage memory that stores thebeginning data and the preceding data.

In such a manner, when data is recorded, ATRAC3 data can be checked.When the decrypter has a temporary storage memory that temporarilystores the beginning data and the preceding data of a block of encrypteddata, the encrypted data can be also checked.

FIG. 37 is a block diagram showing the structure of a recording andreproducing apparatus according to the present invention. A digitalaudio signal is supplied from a CD or Internet to an input terminal 91.The digital audio signal is supplied to an ATRAC3 encoder 92. The ATRAC3encoder 92 performs a highly efficient encoding process for the digitalaudio signal so as to compress it.

The digital audio signal compressed by the ATRAC3 encoder 92 isconverted into blocks corresponding to the sound unit (SU).

The data length of the sound unit is variable in the range from 48 bytesto 256 bytes. This is because the ATRAC3 encoding method allows data tobe compressed at a variable rate.

A fixed value generating device 93 outputs a fixed value VF1 at apredetermined timing. An adding device 95 adds the fixed value VF1 thatis output from the fixed value generating device 93 to the blocksegmented compressed digital audio signal that is output from the ATRAC3encoder 92.

The timing at which the adding device 95 adds the fixed value VF1 to thecompressed digital audio data is controlled by a timing controllingdevice 94.

The timing controlling device 94 may control the timing so that thefixed value VF1 is added to the first one of 50 sound units as anencoding unit as will be described later.

In this case, the timing controlling device 94 counts block informationthat is output from the ATRAC3 encoder 92 so as to control the fixedvalue generating device 93.

Alternatively, the timing controlling device 94 may add the fixed valueVF1 to all sound units that are output from the ATRAC3 encoder 92.

In this case, the fixed value is extracted at the timing of whichencrypted data is decrypted (at intervals of 50 sound units). In thiscase, the fixed value added to the remaining sound units is discarded.

The compressed digital audio signal and the fixed value added by theadding device 95 are encrypted by an encrypter 96 with a key that isoutput from a key storing portion 97 corresponding to a predeterminedencrypting process. According to the embodiment of the presentinvention, the encrypting process is performed corresponding to DES(Data Encryption Standard).

The compressed digital audio signal and the fixed value encrypted by theencrypter 96 are recorded as predetermined blocks to a non-volatilememory 98.

In the above-described example, the fixed value generating device 93generates only one fixed value that is VF1. Alternatively, the fixedvalue generating device 93 may generate a plurality of fixed valuescorresponding to the number of audio channels.

In addition, according to the present invention, as described above,since the variable rate compressing method is used, fixed values may bevaried corresponding to compression rates.

When encrypted data is decrypted, a digital audio signal that has beenencrypted and compressed is read from the non-volatile memory 98. Thedigital audio signal is decrypted by a decrypter 99 with a key that isoutput from a key storing portion 100.

The digital audio signal that has been decrypted by the decrypter 99 isoutput as blocks of ATRAC3 data.

The fixed value VF is added to the ATRAC3 data at predeterminedintervals.

A subtracting device 102 separates the ATRAC3 data from the fixed valueVF at the timing controlled by the timing controlling device 101. Theblock information that is output from the decrypter 99 is supplied tothe timing controlling device 101. The timing controlling device 101controls the timing at which the fixed value is extracted.

A comparing device 104 compares the fixed value VF extracted by thesubtracting device 102 with the fixed value stored in the fixed valuememory 103.

When they match, the comparing device 104 determines that the encrypter96 and the decrypter 99 have normally performed the encrypting processand the decrypting process, respectively.

When the encrypting process and the decrypting process have beennormally performed as the compared result of the comparing device 104,the compared result allows the ATRAC3 decoder 105 to decode the ATRAC3data.

On the other hand, when the encrypting process and the decryptingprocess have been abnormally performed as the compared result of thecomparing device 104, the compared result prohibits the ATRAC3 decoder105 from decoding the ATRAC3 data.

Thus, depending on whether or not the encrypting process and thedecrypting process have been normally performed, the decoding processfor the compressed audio data is permitted or prohibited. When audiodata is encoded, if fixed values corresponding to channels are added,the fixed values are pre-stored to the fixed value memory 103. Whenaudio data is decoded, the comparing device 104 compares the fixedvalues stored in the fixed value memory 103 with the fixed value VFextracted by the subtracting device 104 so as to detect an audiochannel. Corresponding to the detected audio channel, the decompressingprocess of the ATRAC3 decoder 105 is controlled.

In the case that fixed values corresponding to compression rates areadded, the fixed values are pre-stored in the fixed value memory 103.The comparing device 104 compares the fixed values stored in the fixedvalue storing memory 103 with the fixed value VF extracted by thesubtracting device 102 so as to detect a compression rate. Correspondingto the detected compression rate, the decompressing process of theATRAC3 decoder 105 is controlled.

According to the present invention, even if audio data has beenencrypted, corresponding to the value of one byte of the first SU ofeach block, it can be determined whether or not the block is normal.Thus abnormal reproduced data can be prevented from being output. Whendata that has been recorded is reproduced, if it becomes abnormal, itcan be prevented from being reproduced. In addition, the compressionmode can be detected. Thus, a confusion of which different compressionmodes are combined can be prevented.

1. A recording apparatus, comprising: compression process means forcompressing an input digital signal and segmenting the compresseddigital signal into blocks; fixed value generating means for generatinga predetermined fixed value; adding means for adding the fixed valuegenerated by said fixed value generating means at a predetermined timingto the blocks of the digital signal compressed by said compressionprocess means; encrypting means for encrypting the fixed value and thecompressed digital signal added by said adding means; and recordingmeans for recording the fixed value and the compressed digital signalencrypted by said encrypting means to a recording medium.
 2. Therecording apparatus as set forth in claim 1, wherein the record mediumis attachable/detachable to/from the recording apparatus.
 3. Therecording apparatus as set forth in claim 1, wherein the record mediumincludes a non-volatile memory.
 4. The recording apparatus as set forthin claim 1, wherein the fixed value generated by said fixed valuegenerating means is varied corresponding to a compression rate.
 5. Therecording apparatus as set forth in claim 1, wherein the digital signalis a digital audio signal, and wherein the fixed value generated by saidfixed value generating means is varied corresponding to a channel. 6.The recording apparatus as set forth in claim 1, wherein the fixed valueis added to the first block of the plurality of blocks by said addingmeans.
 7. The recording apparatus as set forth in claim 1, wherein thefixed value is added to all blocks of the plurality of blocks by saidadding means.
 8. A recording method, comprising the steps of:compressing an input digital signal and segmenting the compresseddigital signal into blocks; generating a predetermined fixed value;adding the generated fixed value at a predetermined timing to the blocksof the compressed digital signal; encrypting the fixed value and thecompressed digital signal that have been added; and recording the fixedvalue and the compressed digital signal that have been encrypted to arecord medium.
 9. The recording method as set forth in claim 8, whereinthe record medium is attachable/detachable to/from a recordingapparatus.
 10. The recording method as set forth in claim 8, wherein therecord medium includes a non-volatile memory.
 11. The recording methodas set forth in claim 8, wherein the fixed value is varied correspondingto a compression rate.
 12. The recording method as set forth in claim 8,wherein the digital signal is a digital audio signal, and wherein thefixed value is varied corresponding to a channel.
 13. The recordingmethod as set forth in claim 8, wherein the fixed value is added to thefirst block of the plurality of blocks.
 14. The recording method as setforth in claim 8, wherein the fixed value is added to all blocks of theplurality of blocks.